In forming a nitride silicon film, there is a duration until the film starts to be adhered (hereinafter, referred to as an incubation duration) at an initial stage of the film formation. There is a known example of improving the incubation duration. In such an example, in forming a SiN-based insulating film on an SiO-based insulating film, the SiO-based insulating film is formed under an air-tight atmosphere, and then rapidly thermally nitridated and subjected to CVD in sequence, without performing RCA cleansing, while being maintained in state of being blocked from the atmosphere.
Also, there is a method for forming a silicon-containing film such as a silicon nitride film, or the like through plasma chemical vapor deposition. In this method, an ammonia radical is sufficiently adsorbed to a surface of an object to be processed before the silicon-containing film is formed. Thereafter, a silicon precursor such as aminosilane, or the like is reacted with the ammonia radical to form a silicon nitride.
In forming the silicon nitride film, there is an incubation duration. Thus, at the initial stage of film formation, the silicon nitride film exists in the form of islands, rather than being uniformly attached. Accordingly, the silicon nitride film in a very thin film state has poor step coating characteristics, poor physical characteristics that a film thickness or film quality are not uniform, and poor electrical characteristics such as insulating characteristics.